driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

When using Ubuntu OS, the realtek phy driver is loaded by default
instead of the generic PHY driver. However, the set_loopback
interface is not added to the realtek phy driver. As a result,
the phy selftest fails.

This patch adds the set_loopback interface to the realtek phy driver
so that the phy selftest can run properly.
Signed-off-by: NYufeng Mo <moyufeng@huawei.com>
Reviewed-by: Nlipeng <lipeng321@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>